Descartes Highlands
The Descartes Highlands sits on the near side of Earth's Moon, surrounding a feature named Descartes crater. Before 1972, scientists believed this area held abundant volcanic material. They thought the formations resulted from lavas more viscous than those creating the Lunar mare. Visual analysis of the features supported this theory for decades. Apollo 16 changed that understanding completely. Commander John Young and his crew found rocks that were not volcanic in origin. Instead, they discovered breccias composed of fragments from several lunar impacts. These rocks likely came from debris generated by large impact events like the one forming Mare Nectaris. The landscape itself is an undulating terrain covered with old and new sharp rimmed craters. Some floors of these craters contained glass similar to that found at Taurus-Littrow during Apollo 17. Young described the arrangement of this glass as looking exactly like dried mud.
All preceding Apollo missions had sampled Lunar mare material either directly or indirectly. Mission planners needed a landing site in the Lunar highlands to investigate different materials. Two sites received serious consideration: the Descartes site and the crater Alphonsus. The Descartes Highlands was selected to enable astronauts John Young and Charles Duke to sample the prominent Descartes and Cayley formations. These two formations cover much of the near side of the Moon. Priority was given to locating samples older than the Imbrium impact. This goal aimed to provide insight into the geologic timeline and composition of the Moon. North Ray and South Ray craters became key targets because natural excavations there exposed material from the prominent formations. The selection process prioritized finding evidence of ancient history rather than volcanic activity.
Apollo 16 crews discovered specific geological features within the crater floors of the region. They found layers of glass resembling dried mud scattered across the landscape. Commander John Young noted this unique appearance during his time on the surface. The glass appeared similar to that found at Taurus-Littrow, another Apollo 17 landing site. These findings challenged previous assumptions about the area's formation. Scientists now understood that many rocks were breccias formed by multiple impacts. The layering sequence revealed an overlap between the Cayley and Descartes formations. This discovery proved vital for understanding how the highlands developed over billions of years. The visual evidence provided a clear alternative to the long-held volcanic theories.
Astronauts John Young and Charles Duke traveled to Sudbury, Ontario in July 1971. They visited this Canadian location to examine shatter cones left by a large meteor impact. Sudbury exhibits substantial evidence of shatter cone geology relevant to lunar studies. The team used these field observations to validate their lunar impact hypotheses. Back on the Moon, they determined the region's topography resulted from meteor impact instead of volcanic activity. This connection between Earth and Moon geology strengthened their conclusions. The visit helped them identify specific rock types expected in the highlands. It also prepared them to recognize impact debris when they arrived at the landing site. The trip served as practical training for interpreting complex geological data.
John Young and Charles Duke drove across North Ray and South Ray craters during their mission. These two features were prominent elements in the immediate landing area. The astronauts sampled material directly from these locations to study the underlying formations. Their routes allowed them to access naturally excavated samples from both Cayley and Descartes layers. An aerial photo shows the Apollo 16 mission traverses labeled clearly across the terrain. Viewers can see Stone Mountain and the valley between it and the Smoky Mountains. Ravine Crater appears visible at the upper left portion of that northern view. Station 4 sat near Cinco Crater where the crew paused to collect samples. Every mile driven added critical data about the age and composition of the highlands. The physical journey across these craters remains a key part of the mission legacy.
Common questions
Where is the Descartes Highlands located on Earth's Moon?
The Descartes Highlands sits on the near side of Earth's Moon, surrounding a feature named Descartes crater. This area covers much of the near side and includes prominent Cayley and Descartes formations.
What did Apollo 16 astronauts find in the Descartes Highlands instead of volcanic rock?
Commander John Young and his crew found rocks that were not volcanic in origin but rather breccias composed of fragments from several lunar impacts. These rocks likely came from debris generated by large impact events like the one forming Mare Nectaris.
When was the Descartes Highlands selected as an Apollo landing site?
Mission planners selected the Descartes Highlands before 1972 to investigate different materials than those found in Lunar mare regions. The selection process prioritized finding evidence of ancient history rather than volcanic activity.
Why did John Young and Charles Duke visit Sudbury Ontario in July 1971?
Astronauts John Young and Charles Duke traveled to Sudbury Ontario in July 1971 to examine shatter cones left by a large meteor impact. They used these field observations to validate their lunar impact hypotheses and prepare for interpreting complex geological data.
Which craters did John Young and Charles Duke drive across during the Apollo 16 mission?
John Young and Charles Duke drove across North Ray and South Ray craters during their mission to sample material directly from these locations. Their routes allowed them to access naturally excavated samples from both Cayley and Descartes layers.